1. Field of the Invention
The present invention relates to a paper supply system for installing and detaching paper supply cassettes in and from a copying machine.
2. Description of the Prior Art
Although there are known a two-stage copying machine, in which two paper supply cassettes can be positioned at one time, a three-stage copying machine, in which three paper supply cassettes can be positioned at one time, a fourth-stage copying machine, in which four paper supply cassettes can be positioned at one time, and the like, in general there are only paper supply cassettes of small volume type housing about 250 pieces of copying paper and paper supply cassettes of large volume type housing about 500 pieces of copying paper. Copying paper sheets of B5 size and A4 size provided in JIS, which are used frequently, should be housed in a paper supply cassette of large capacity. On the contrary, copying paper sheets of B4 size and the like, which are large-sized and used at lower frequencies, should be housed in a paper supply cassette of smaller capacity, since such paper supply cassette otherwise would be relatively heavy, thereby resulting in the disadvantage of difficulty of handling and the possibility that the copying papers become deteriorated by moisture and the like. In addition, at present paper supply cassettes of small volume type housing about 250 pieces of copying paper and those of large volume type housing about 500 pieces of copying paper are used since copying papers are frequently packaged with 500 pieces as a unit. Although copying machines are known in which paper supply cassettes of small volume type are positioned in some multi-stage cassette receiving spaces and paper supply cassettes of large volume type are positioned in the remainder of such multi-stage spaces, only paper supply cassettes of small volume type can be positioned in spaces for housing paper supply cassettes of small volume type, and only paper supply cassettes of large volume type can be positioned in spaces for housing paper supply cassettes of large volume type, without interchange therebetween. As a result, such machines are disadvantageous for practical use. In such arrangement, a cassette-holding member extends across substantially the entire width of the space for housing the paper supply cassette, and the bottom surface of the cassette is supported over the entire width thereof.